Summary of the Draft Revision

- 1 -

5/BL/9-E

Radiocommunication Study Groups /
Source:Document 5/206(Rev.1)(edited) / Document 5/BL/9-E
28 January 2011
English only
Radiocommunication Study Group 5
draft revision of RECOMMENDATION ITU-R F.1191-2
Bandwidths and unwanted emissionsof digital fixed service systems

Summary of the draft revision

This revision includes the following:

–addition of the scope;

–removal of text duplicating references in the Radio Regulations;

–addition of the concept of spurious domain and out-of-band domain based on the Radio Regulations;

–review and reorganization of the paragraphs of considering, recognizing, noting and recommends including the associated Notes;

–updating of other old information in the text.

DRAFT REVISION OF RECOMMENDATION ITU-R F.1191-2

Necessary and occupied Bbandwidths and unwanted emissions
of digital fixed service systems[*]

(Question ITU-R 119/9)

(1995-1997-2001)

Scope

This Recommendation gives an explanation of basic terms relating to unwanted emissions and bandwidths of digital fixed service systems to clarify the application of definitions in the Radio Regulations and Recommendations ITU-R SM.328 and ITU-R SM.329, as well as guidance consideration on these subjects for use for system or equipment designer of fixed service systems.

Considerations are also made on the occupied bandwidth of multicarrier systems and requirements for outof-band emissions for systems used in the block-based assignment.

The ITU Radiocommunication Assembly,

considering

a)that the definitions of necessary and occupied bandwidth and allocated band are reported in Nos.1.152, 1.153 and 1.16 of the Radio Regulations (RR) respectively;

b)that the definitions of unwanted, out-of-band and spurious emissions are reported in RR Nos.1.146, 1.144 and 1.145 respectively;

ac)that it is necessary for designers of digital fixed service systems (DFSS) to give guidance for the application of these definitionsterms relating to bandwidths and unwanted emissionsto digital fixed service systems (DFSS);

bd)that it is relatively unlikely that out-of-band emissions from DFSS will cause significant interference into systems operating in adjacent bands, because:

–the power spectrum of a DFSS decays rapidly outside the occupied bandwidth;

–the e.i.r.p. of line-of-sight DFSS is low or medium;

–trans-horizon DFSS employing a high e.i.r.p. are not widely used;

ce)that from the viewpoint of interference into other systems sharing the same frequency band, interference due to out-of-band emissions will be, in general, less significant than that due to emissions within the necessary bandwidth;

df)that intra-system interference related problems, which may be caused by unwanted emissions, are normally taken into account by DFSS designers;

g)that bands are allocated to fixed services on a primary or co-primary basis, where a radio-frequency (RF) channel arrangement has been established by a relevant ITU-R Recommendation or by a national regulatory authority;

h)that transmitter frequencies should be determined so that out-of-band emissions do not cause harmful interference outside the allocated band in accordance with RR No.4.5; the transmitters on the RF channels at the allocated band edges should comply with the general necessary bandwidth and assignment criteria required by RR No.1.147;

ej)that at the allocated band edges, RF bandsedge guardband ZS, as defined in Recommendation ITURF.746, areis given by the relevant ITU-R Recommendations in order to control power spillover into adjacent allocated bands;

fk)that it is not always possible or convenient to make the occupied bandwidth of DFSS smaller than or equal to the bandwidth of the RF channel provided by the relevant RF channel arrangement established for the allocated band by ITU-R or by a national regulatory authority;

g)that in most bands allocated to fixed services on a primary basis, aradiofrequency (RF) channel arrangement is usually established by a relevant ITU-R Recommendation or by a national regulatory authority;

hl)that, within the allocated band, coordination between various fixed service systems,used based on the basis use of a RF channel arrangement, is covered by anspectrum-efficient concept summarized by Recommendation ITU-R F.746 and by the statistical propagation behaviour reported in RecommendationITU-RP.530 and RecommendationITU-RF.1093;

jm)that DFSS, with suitable scrambling applied, have in general a transmitted spectral density and unwanted emissions with power peak factors that may be conservatively considered noise-like;

kn)that DFSS have generate unwanted emissions, composed of both noise-like and discrete components, made upin bothof outof-band and spurious emissions domains, which are not easy to distinguish one from the other;

o)that Recommendation ITU-R SM.329 gives the limits and the reference bandwidth for spurious emissions of all services, including the fixed service;

p)that Recommendation ITU-R SM.329 defines the frequency boundary between spurious and out-of-band emissions as 250% of the necessary bandwidth; however allowance is given for different definitions, and this frequency boundary may be dependent on the type of modulation used, the maximum bit rate in the case of digital modulation, the type of transmitter, and frequency coordination factors. For example, in the case of some digital systems, the frequency boundary may need to differ from the 250% factor (see NOTE 4);

q)that, in fixed service applications, different emissions with different modulation formats and necessary bandwidth may co-exist in the same channel separation; it is therefore convenient, for ease of frequency coordination and for regulatory purposes, to consider the 250% of the constant channel separation as the boundary between out-of-band and spurious emissions, instead of the various different necessary bandwidths of any specific system (see Note 4);

r)that Recommendation ITU-R SM.1541 gives safety net out-of-band limits for most of the services, including the fixed service (see NOTE 1);

s)that on regional or national bases more tighter limits than those given by RecommendationITU-R SM.1541 are commonly applied if such opportunities can be found;

tl)that single or multi-carrier systems are widely used in DFSS;,

u)that the studies required by Question ITU-R 222/1, approved by the Radiocommunication Assembly, 2000 (RA-2000), could have formal and substantial impact to basic definitions used in this Recommendation. It may be necessary to revise this Recommendation in the future to reflect the results of these studies,

noting

a)that Recommendation ITU-R SM.328 gives information on the evaluation of outofband spectral emission for various modulation formats;

b)that RR Appendix 3 depicts tables of spurious emission limits,

b)that Recommendation ITU-R SM.329 gives the limits and the reference bandwidth for unwanted emissions in the spurious domain of all services, including the fixed service;

c)that Recommendation ITU-R SM.1541 gives generic limits for unwanted emissions in the out-of-band domain for most of the services, including the fixed service (seeNote1);

d)that Recommendation ITU-R SM.1539 gives guidance on the variation of the boundary between out-of-band and spurious domains for very narrow-band and very wideband emissions,

recommends

1that the following general definitionsterms should be appliedapply to DFSS:

1.1Occupied bandwidth

The width of a frequency band such that, below the lower and above the upper frequency limits, the mean powers emitted are each equal to a specified percentage /2 of the total mean power of a given emission (RR No.1.153).

1.2Necessary bandwidth

For a given class of emission, the width of the frequency band which is just sufficient to ensure the transmission of information at the rate and with the quality required under specified conditions (RRNo.1.152).

1.31Allocated frequency band

Allocation (of a frequency band): entry in the Table of Frequency Allocations of a given frequency band for the purpose of its use by one or more terrestrial or space radiocommunication services or the radioastronomy service under specific conditions. This term shall also be applied to the frequency band concerned (RR No.1.16).

For DFSS the allocated frequency band may be considered as the overall frequency band allocated to the fixed service on a primary or co-primary basis.

1.42Assigned frequency band

Authorization given by an administration for a radio station to use a radio frequency or radiofrequency channel under specified conditions (RR No.1.18).

For the purpose of this Recommendation this term is may be considered to apply also to a block of spectrum assigned to one or more stations of an operator under a single exclusive license (block-assignment, see examples in Recommendations ITU-R F.1488, ITU-R F.748 and ITURF.749).

Inside a single block-assignment, the operator system designer may, in general, subdivide the block into suitable smaller sub-blocks in order to deploy a radio network in the geographical area where the assignment has been made, within conditions specified above (see Recommendation ITU-R F.1399).

1.53Radio-frequency channel separation

Bandwidth equal to the frequency separation, defined in Recommendation ITU-R F.746, of adjacent channels of the relevant RF channel arrangement established within the allocated frequency band.

1.64Guardband

Bandwidth equal to the frequency separation, defined in Recommendation ITU-R F.746 as ZS, between the nominal centre frequency of the outermost channel of a RF channel arrangement and the limit of the allocated band.

1.7Unwanted emissions

Consist of spurious emissions and out-of-band emissions (RR No.1.146).

For DFSS an example of a typical scenario is reported in Fig.2.

1.8Out-of-band emission

Emission on a frequency or frequencies immediately outside the necessary bandwidth which results from the modulation process, but excluding spurious emissions (RR No.1.144).

1.9Spurious emission

Emission on a frequency or frequencies which are outside the necessary bandwidth and the level of which may be reduced without affecting the corresponding transmission of information. Spurious emissions include harmonic emissions, parasitic emissions, intermodulation products and frequency conversion products, but exclude out-of-band emissions (RR No. 1.145).

1.10Characteristic frequency

A frequency which can be easily identified and measured in a given emission (RR No. 1.149).

1.115Multicarrier system

For the purpose of this Recommendation, multicarrier systems are those Systems where multiple sub-carriers may be transmitted simultaneously from a final output amplifier or an active antenna within an assigned channel of the relevant channel arrangement or a specifically dedicated spectrum slot;

2that the following specific design objectives and definitions terms should be used for DFSS; anillustration of those objectives and definitions can be found in Fig.1;

2.1that, for DFSS, the value of percentage /2 should be taken as 0.5%; this percentage is assumed for single carrier transmitters; when multicarrier systems are concerned, this percentage, with respect to the total power of the whole set of sub-carriers isshould bereduced as a function of the subcarriers number and bandwidth (see Section 3 of Annex 1 for details);

2.2that, for DFSS, the necessary bandwidth is toshould be considered to have the same value as the occupied bandwidth;

2.3that, according to the type of the utilized RF channel arrangement (see Note2), thecapacity and the modulation format of the transmitted signal, similar DFSS could may have anecessary bandwidth which is no more than 20% wider than the radio-frequency channel separation (see Note2); however, since dissimilar systems operating in the same band could may give rise to certain incompatibilities, the relationship between the RF channel separation and the necessary bandwidth requires further study;

2.4that the determination of occupied bandwidth should be done with a spectrum analyser method described in Recommendation ITU-R SM.328 or, whenever possible, by numerical evaluation or integration of the actual emitted spectrum as reported in Annex 1;

2.5that when burst transmission is used (e.g. for time division multiple access (TDMA) DFSS) the evaluation of bandwidths and emissions should be done averaging the power over burst duration;

2.6that DFSS should use suitable scrambling circuitry in order to maintain all the spectral emissions (both wanted and unwanted) independent from the input data stream;

2.7that any unwanted emission which falls at frequencies separated from the centre frequency of the RF channel by less than 250% of the relevant channel separation, where the system is intended to be used, will should generally be considered unwanted emission in the out-of-band domainemission (see Notes4 and5); when DFSS is intended for use in a frequency band where anRF channel arrangement has not been established, the necessary bandwidth should be used, instead of channel separation, in evaluating the 250% boundary;

2.8that any unwanted emission which falls at frequencies separated from the centre frequency of the RF channel by 250% or more of the relevant channel separation, where the system is intended to be used, will should generally be considered unwanted emission in the spurious domainemission (see Notes 4 and 5); when DFSS is intended for use in a frequency band where an RF channel arrangement has not been established, the necessary bandwidth should be used, instead of channel separation, in evaluating the 250% boundary;

2.9that, above and below the limits of the necessary bandwidth, the permissible mean power level of unwanted emission should be less than or equal to 0.5% of the total transmitted mean power taken at the radio antenna port (seeNote3); in case of multicarrier systems this rule is intended to be applied to the outermost sub-carriers;

2.10that, from the viewpoint of the international regulations, it is presentlymay not be necessary to establish any additional limitation on the spectral shape of unwanted emissions from DFSS;

2.11that the levels of spurious emissions, the frequency range for their measurement and the reference bandwidth in which levels are specified should be those defined by Recommendation ITURSM.329 (see Notes 4 and 6). Where exclusive block assignments are made, transmitters operating on sub-channels devised by the licensed operator couldmay, in principle, be exempted, within the block, by the unwanted emissions limit required to be met outside the block; however at country borders this should require agreement between the administration concerned due to the fact that they may have licensed the band in a different way;

2.12that any safety net limits for unwanted emissions in the out-of-band emissionsdomainlimits developed by Radiocommunication Study Group1ITU-R should be considered as an absolute worst-case limit to which any new DFSS design should conform;

2.13that, without other specific agreement between administrations sharing the same band edge, the digital fixed radio transmitters operating on the outermost channel frequencies of a RF channel arrangement should have an occupied bandwidth so that the outermost part of it with respect to the centre frequency of the channel, when added to the absolute value of the frequency tolerance (see Note75), results in a bandwidth smaller than or equal to the value of ZS as defined in § 1.64.;

Note1–In general terms the generic limit is considered to be a generally worst-case envelope based on the least restrictive out-of-band emission limits successfully used as national or regional regulations in areas having a high radiocommunication density and representing asignificant portion of the radiocommunication manufacturing base. The word “generally” isintended to cover exceptional cases where a particularly unrestrictive mask may have been used, e.g. to encourage equipment development in an unattractive band (see noting c)).

2.14that the following Notes 2-5 should be considered as part of this Recommendation.

Note1–In general terms the safety net is considered to be a generally worstcase envelope based on the least restrictive out-of-band emission limits successfully used as national or regional regulations in areas having a high radiocommunications density and representing asignificant portion of the radiocommunications manufacturing base. The word “generally” isintended to cover exceptional cases where a particularly unrestrictive mask may have been used, e.g. to encourage equipment development in an unattractive band.

NOTE2–See Recommendation ITU-R F.746 for definitions of alternated, co-channel mode band reuse and interleaved mode band reuse RF channel arrangements. Channel separation is defined as XS/2 for alternated frequency channel arrangements and XS for co-channel and interleaved frequency channel arrangements.

NOTE3–Due to possible compatibility problems, caution should be exercised when applying this Recommendation to high capacity systems, bands which have dissimilar systems in adjacent channels, and bands which are shared with other services.

NOTE4–Recommendation ITU-R SM.1539 also gives guidance on boundary variations where very narrow-band or very wideband emissions are concerned. In addition, Aas Recommendation ITURSM.329 allows for boundary values different than 250%, the following is provisionally recommended for DFSS operating above 1GHz with channel separation less than 2MHz:

–that the boundary between the spurious and out-of-band emissions is established as 500% of the channel separation;

–that the reference bandwidth is 100kHz in the frequency range between this boundary and 20MHz of the nominal centre frequency;

and also for DFSS operating above 1 GHz with transmitter power 20 W or more and with channel separation between 2 MHz and 14 MHz:

–that the boundary between the spurious and out-of-band emissions is established as 250% of the channel separation;

–that the reference bandwidth is 100kHz in the frequency range between this boundary and 70MHz of the nominal centre frequency.

NOTE5–When the fixed service system is intended for use in a frequency band where an RF channel arrangement has not been established, the necessary bandwidth should be used, instead of channel separation, in evaluating the 250% boundary.

NOTE6–It is recognized that the reference bandwidth of 1MHz may result in spectral density requirement of up to 24 dB more stringent than with the 4 kHz bandwidth given in the 1995 version of this Recommendation.

NOTE75–The precise specification of frequency tolerance values is are left to the national regulatory authorities.

Figure 1

Unwanted emission attenuation objectives and bandwidthdefinitions of DFSS

(No change except for the title)

Annex 1

(No change)

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[*]This Recommendation should be brought to the attention of Radiocommunication StudyGroup1.